The festive special itself will feature Doctors One and Twelve crossing paths, seemingly as they both attempt to stave off an imminent regeneration.

'Twice Upon a Time' is the swansong for Peter Capaldi, Pearl Mackie and their head writer Steven Moffat, ahead of the arrival of new showrunner Chris Chibnall, new lead actress Jodie Whittaker and her TARDIS team featuring Bradley Walsh next year.

Photo credit: BBC Worldwide/Simon Ridgway

However, this upcoming episode might not be the end for the First Doctor. David Bradley recently expressed interest in reprising the role during the Jodie Whittaker era.

"If they asked me, yes, I'd bite their hand off. I think it would be fun," he said. "So far, I'm very happy to have been involved in both [Doctor Who and An Adventure in Space of Time].

"It's quite something, you never expect in your career – something you watched when you were young and never imagined you'd be involved in something so iconic. As I say, it's a late treat!

"If someone wanted to do that, I'd be very interested, yeah. Of course."

Photo credit: BBC

Children in Need airs a sneak peek at 'Twice Upon a Time' next Friday night (November 17) in the BBC One portion of the evening, at some point between 7.30pm and 10pm.